The present invention is generally directed to a device and method for reinforcement of the cardiac wall. The invention is particularly suited for the treatment of cardiac disease which result in a trial or ventricular dilation. The invention provides reinforcement of the cardiac wall during diastolic chamber filling to prevent or reduce cardiac dilation in patients known to have experienced such dilation or who have a predisposition for such dilation occurring in the future. The cardiac reinforcement structure is typically applied to the epicardial surface of the heart.
Cardiac dilation occurs with different forms of cardiac disease, including heart failure. In some cases, such as post-myocardial infarction, the dilation may be localized to only a portion of the heart. In other cases, such as hypertrophic cardiomyopathy, there is typically increased resistance to filling of the left ventricle with concomitant dilation of the left atria. In dilated cardiomyopathy, the dilation is typically of the left ventricle with resultant failure of the heart as a pump. In advanced cases, dilated cardiomyopathy involves the majority of the heart.
With each type of cardiac dilation, there are associated problems ranging from arrhythmias which arise due to the stretch of myocardial cells, to leakage of the cardiac valves due to enlargement of the valvular annulus. Devices to prevent or reduce dilation and thereby reduce the consequences of dilation have not been described. Patches made from low porosity materials, for example Dacron(trademark), have been used to repair cardiac ruptres and septal defects, but the use of patches to support the cardiac wall where no penetrating lesion is present has not been described.
Drugs are sometimes employed to assist in treating problems associated with cardiac dilation. For example, digoxin increases the contractility of the cardiac muscle and thereby causes enhanced emptying of the dilated cardiac chambers. On the other hand, some drugs, for example, beta-blocking drugs, decrease the contractility of the heart and thus increase the likelihood of dilation. Other drugs including angiotensin-converting enzyme inhibitors such as enalopril help to reduce the tendency of the heart to dilate under the increased diastolic pressure experienced when the contractility of the heart muscle decreases. Many of these drugs, however, have side effects which make them undesirable for long-term use.
Accordingly, there is a need for a device that can reduce or prevent cardiac dilation and reduce the problems associated with such dilation.
The present invention is directed to a device and method for reinforcement of the cardiac wall. According to the invention, a cardiac reinforcement device includes a biomedical material which can be applied to the epicardial surface of the heart and which expands to a predetermined size that is selected to constrain cardiac expansion beyond a predetermined limit. A biomedical material suitable for a cardiac reinforcement device can be an elastic or nonelastic mesh or non-mesh material.
In one embodiment, a cardiac reinforcement device is a biomedical material in the form of a patch. The size of the patch is selected to locally constrain cardiac expansion.
In another embodiment, a cardiac reinforcement device is a biomedical material shaped as a jacket with a predetermined size selected for the jacket to surround the epicardial surface of the heart and circumferentially constrain cardiac expansion. In one embodiment, a cardiac reinforcement jacket may be applied to the epicardial surface via a minimally invasive procedure such as thorascopy.
A cardiac reinforcement jacket can include a securing arrangement for securing the jacket to the epicardial surface of the heart. The cardiac reinforcement jacket can also include a mechanism for selectively adjusting the predetermined size of the jacket around the epicardial surface of the heart. The adjustment mechanism can include a slot having opposing lateral edges which when pulled together decrease the volumetric size of the jacket. In an alternative embodiment, a selective size adjustment mechanism can include an inflatable member mounted between the jacket and the epicardial surface of the heart. Inflation of the inflatable member provides for reduction in the volumetric size of the jacket.
A cardiac reinforcement device of the invention can be used to treat cardiomyopathy or to reduce the diastolic volume of the heart.